A fuel supply apparatus for supplying fuel to the internal combustion engine disclosed in the U.S. Pat. No. 5,078,167 or No. 5,195,494 have been conventionally known. In the structure of U.S. Pat. No. 5,078,167, a pressure regulator disposed below a fuel filter returns surplus fuel into a fuel tank before the fuel enters a fuel filter. On the other hand, in the structure of U.S. Pat. No. 5,195,494, a pressure regulator disposed in a fuel pump inside a fuel tank returns surplus fuel into the fuel tank from the fuel pump. Theses apparatuses reduce the rise of a temperature inside the fuel tank by eliminating returned surplus fuel, i.e., return fuel from the internal combustion engine to the fuel tank.
However, when the return fuel is eliminated, since the fuel flowing amount in a pipe from the fuel tank to the internal combustion engine as well as in a passage of a fuel injection apparatus mounted on the internal combustion engine is decreased, water mixed in the fuel may be accumulated, and corrosion of metal parts and malfunction of the apparatuses may be caused due to the water.
The above-described conventional technology may cause the water to be sent to the internal combustion engine with the fuel, in addition, the water mixed in the fuel becomes water drops inside the housing of the fuel filter and the water drops may be sent to the internal combustion engine as they are.